Many applications exist today for lamps powered by rechargeable batteries in combination with automatic battery charger circuits adapted to operate from AC power lines. One particular application where such circuits are used is in emergency lights which provide emergency illumination upon failure of AC power. Generally, such emergency illumination is only required for a short period following the failure of AC power to permit safe exit from dangerous, darkened areas, such as stairways, and to provide time for procuring other means of temporary illumination. However, most emergency lights available today continue to provide illumination for as long as the power failure continues, until the battery is fully discharged. Since most rechargeable batteries suffer damage and/or have their useful lives shortened when discharged beyond a certain point, such operation requires that batteries be frequently checked and replaced following each power outage. While low-charge cut-off circuits are known, the addition of such circuitry to the power failure detection circuitry and full-charge monitor circuitry already required for proper rechargeable emergency light operation entails even more complication and expense. Additionally, in many solid-state emergency light circuits, the loss of AC power is detected by the circuitry which requires direct connection to the power line voltage, creating potential safety habits.